The frustrating search for Malaysia Airlines Flight 370 has highlighted how little is known about the world's oceans. The sea floor in the search area is only very roughly mapped. And there is just rudimentary understanding of the behavior of sound waves in the deep sea and the motion of surface currents, which made the hunt for black box beacons and debris all the more difficult. The plane's true route and likely point of crashing into the sea could have been known with precision if existing technologies to stream black box data from planes had been implemented. Finding the plane now will require an unprecedented search effort.